using System; class MyClass { } class Test<T> { public T obj; public Test() { obj = default(T); } } class DefaultDemo { public static void Main() { Test<MyClass> x = new Test<MyClass>(); if(x.obj == null) Console.WriteLine("x.obj is null."); Test<int> y = new Test<int>(); if(y.obj == 0) Console.WriteLine("y.obj is 0."); } }